This invention relates to dry sprinkler arrangements for fire protection systems and, more particularly, to new and improved dry sprinkler arrangements which more effectively convey water to a sprinkler deflector.
Conventional dry sprinklers for fire protection systems include a pipe connected at one end to a sprinkler head having a thermally responsive device and a deflector and at the other end to a water supply line and they include a valve or sealing plug at the end of the pipe joined to the water supply line to prevent pressurized air, nitrogen or water from entering the pipe until the thermally responsive device in the sprinkler head has been actuated. Such dry sprinkler arrangements usually include a rod or tube within the pipe separating the sprinkler head from the sealing plug to retain the plug in its sealing position until the sprinkler has been actuated. Following actuation, the inner rod or tube moves away from the supply line and projects out of the pipe toward the sprinkler head deflector, partially interfering with the flow of water toward the deflector. Moreover, after actuation the plug may be retained within the pipe in a position which also interferes with the flow of water through the pipe toward the sprinkler head.
Certain prior art dry sprinkler arrangements have been proposed to alleviate these problems, but they often require complex and potentially unreliable structural arrangements. For example, U.S. Pat. Nos. 2,180,258, 3,061,015, 3,080,000, 4,417,626, and 4,228,858 disclose dry sprinkler arrangements in which a loose plug releasably held in a sealing position at the end of the dry sprinkler adjacent to the water supply is intended to pass through the dry sprinkler and be ejected from the sprinkler after actuation. These arrangements require releasable plug-holding elements, such as balls or the like, which are designed to move away from a plug-supporting position and to be ejected through the dry sprinkler with the plug when the sprinkler is actuated.
U.S. Pat. No. 5,188,185, on the other hand, discloses a dry sprinkler arrangement having a sealing plug at the end adjacent to the water supply line which is pivotally mounted on the projecting ends of a yoke member supported from the sprinkler head by an internal tube extending through the dry sprinkler. A spring surrounding the yoke member extends between projecting tabs on the yoke member and the adjacent end of a water supply line connection at the water pipe to urge the yoke member toward the sprinkler head. The water supply line connection has a radially enlarged opening providing room for the plug to be rotated 90.degree. on the yoke when the sprinkler is actuated so as to displace the plug from the path of water flowing through the sprinkler head. Such prior art systems are complex in structure and expensive to manufacture.